Good morning. This is Graham Predeger with the Chugach National Forest Avalanche Information Center on Monday, April 9th at 7am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).
There is a MODERATE avalanche danger today for the core advisory area. Small, human triggered slab avalanches are possible in specific areas where buried surface hoar persists. A second concern comes in the form of wet avalanches. Anticipate wet activity on any slopes with a west or south tilt as the sun makes its way around the compass. A LOW avalanche danger will exist this morning at all elevations on west, south and east aspects until temperatures are enough to break down surface crusts. On north aspects above tree line, the danger is MODERATE all day.
With clear skies and a solid overnight freeze, all elevations on east, west and south aspects are sporting a stout, semi-supportable crust. Human triggered avalanches will be unlikely until the sun has a chance to heat up the surface and penetrate these layers. Once surface crusts become unsupportable and punchy, avalanche danger will rise to moderate on sun-affected slopes. Higher elevation (above tree line) north facing slopes continue to harbor dry surface snow over buried surface hoar. Shallow, this surface hoar is still proving reactive to a skiers weight and not bonding particularly well with neighboring layers.
Primary Concern- Persistent Slabs
These shallow persistent slabs will continue to be a problem for the foreseeable future as this buried surface hoar is akin to a stubbed toe that just won’t seem to heal. Though mostly manageable (8-16″) these slabs are running very fast when initiated and have the potential to cause harm if you find yourself in or above high consequence terrain such as cliffs or rocks. These persistent slabs are found in north facing terrain above tree line, precisely where most folks are seeking out quality snow.
Secondary Concern – Wet Avalanches/Glide Avalanches and Cornices
Don’t forget the sunscreen today! As the sun reaches its peak solar radiation around 1-3PM, south and west facing slopes will begin to lose their structural integrity. Once you can step off your skis or snowmachine and the surface crust no longer supports you, this is a good sign to limit your exposure to steep sun-affected slopes. Some heat-induced shallow wet slabs were observed yesterday in the Girdwood valley as well, comprised primarily of Saturday’s new snow. Additionally, glide cracks and cornices are becoming further stressed with several hours of direct sunlight each day. It will be a good idea to limit your exposure to these features as you travel through the mountains today and for the rest of the season.
Saturday’s unsettled weather brought 2-3″ of snow to the Girdwood valley and less at Turnagain pass, which melted quickly as the sun came out for Easter Sunday. We experienced a light freeze at sea level yesterday morning as the weak low pressure moved out of the area and skies cleared.
Today and for the next couple of days, a high-pressure ridge will dominate south central Alaska weather. This stable air mass will provide us with mostly clear skies, light winds and as long as nights are clear, below-freezing temperatures at sea level. Expect temperatures to reach the high 30’s today at 1000′, becoming increasingly cooler as you gain elevation.
CNFAIC Weather Page and the NWS forecast
I will issue the next advisory tomorrow morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.